The present invention relates to an electro-therapeutic device for applying a small electric current to the body. The application of small currents to particular points of the body, such as acupuncture points, biologically active trigger points, neural junctions etc., has been found to provide relief for certain ailments. Such points may be characterised by having a low electrical resistance compared to adjacent areas on the body.
GB1416141 describes a hand-held device in which a casing forms one electrode and is gripped in the hand. A second electrode projects from an end of the casing and is pressed against the body. A switch connects a 9V DC power supply across the electrodes. As the second electrode is passed over the surface of the body it encounters low resistance points so that a higher current flows through the body from the hand to the second electrode. Stimulation of the body at such low resistance points by the application of a low current which passes through the low resistance point can give a desirable therapeutic effect. The device of GB1416141 includes a light emitting diode whose brightness is intended to vary with the current flowing through the body, and hence provide a rough visual indication of when a low resistance point has been reached.
EP0145176 describes a hand-held device in which the two electrodes are mounted at the tip of a casing. A DC voltage is applied across the electrodes and a low resistance point on the body is detected by an increase in current between the electrodes. This is displayed visually by a row of light emitting diodes, and audibly by a speaker in the casing which sounds when a low resistance point is reached. The user then operates a switch to apply a higher, pulsed, DC current to stimulate the body at the low resistance point. Circuitry can be provided to apply the higher current automatically when the detected resistance falls below a predetermined value.
These prior art devices suffer from a number of drawbacks. The device of EP0145176 will not operate efficiently when the skin is moist, for example due to perspiration. In such conditions the moist skin forms a low resistance path which shunts the current between the electrodes, so that the device always measures a low resistance and any treatment current will not pass under the skin to the treatment points.